1. Technical Field
The present invention relates to coded modulation, and in particular, to systems and methods for data transport employing optimum signal constellation design (OSCD)-based low density parity check (LDPC)-coded coherent optical-orthogonal frequency division multiplexing (CO-OFDM).
2. Description of the Related Art
As the response to never ending demands for higher data rates and distance independent connectivity, 100 Gb/s Ethernet (GbE) standard has been already adopted, and higher speeds (e.g., 400 GbE, 1 TbE, etc.) have become the research focus of many researchers. IEEE recently ratified the 40/100 GbE standard IEEE 802.3ba. As the operating symbol rates increase, the deteriorating effects of fiber nonlinearities and polarization-mode dispersion (PMD) reach levels that inhibit reliable communication over the optical fiber network.
High speed (e.g., Terabit) optical Ethernet technologies may be affected by the limited bandwidth of information-infrastructure, high energy consumption, and heterogeneity of optical networking infrastructure, for example. As the operating symbol rates increase, the deteriorating effects of fiber nonlinearities and polarization-mode dispersion (PMD) reach levels that inhibit reliable communication over the optical fiber network. Furthermore, in the context of high-speed optical communication systems, not only the error correction performance but also the complexity of a coded modulation system plays a crucial role. To reach ultra high-speed (e.g., 1 Tb/s) serial date rates, extremely large signal constellation sizes are currently required for polarization-division multiplexed (PDM) single-carrier QAM systems, with commercially available symbol rates. However, as a signal constellation grows in size to increase its SE, so does the optical signal-to-noise ratio (OSNR) that is required to achieve a certain bit error ratio (BER) using conventional systems.